Preservation of foodstuffs with synergistic antioxidant composition comprising ascorbic acid and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid

ABSTRACT

Synergistic antioxidant compositions useful as additives for edible fats and oils comprising ascorbic acid and rac. 6-hydroxy2,5,7,8-tetramethychroman-2-carboxylic acid are described.

EJnite States atem [191 Cort [451 Sept. 2, 1975 [75] Inventor: WinifredCort, Little Falls, NJ.

[73] Assignee: Hoffmann-La Roche Inc., Nutley,

[22] Filed: Apr. 29, 1974 [21] Appl. No.: 465,217

[52] US. Cl. 426/545; 426/546; 426/610;

[51] Int. Cl. A23D 5/04; C09K 15/06; C07D 259/00 [58] Field of Search426/182, 183, 181, 197,

[56] References Cited UNITED STATES PATENTS 2,511,428 6/1950 Buxton426/228 3,313,826 4/1967 Gale 426/228 3,364,234 1/1968 Schoenewaldt...426/328 3,502,594 3/1970 Ahrens 260/3985 FOREIGN PATENTS OR APPLICATIONS45-29413 9/1970 Japan .L 426/183 949,715 2/1964 United Kingdom 260/3455OTHER PUBLICATIONS Chemical Abstracts, Vol. 80, 1974, article 133243,Nakamura.

Primary Examiner.lack Sofer Assistant ExaminerCurtis P. RibandoAtlorney, Agent, or Firm-Samuel L. Welt; Jon S. Saxe; R. I-Iain Swope [57] ABSTRACT Synergistic antioxidant compositions useful as additives foredible fats and oils comprising ascorbic acid and rac.6-hydroxy-2,5,7,8-tetramethychroman-2- carboxylic acid are described.

8 Claims, N0 Drawings PRESERVATION OF FOODSTUFFS WITH SYNERGISTICANTIOXIDANT CONWOSITION COMPRISING ASCORBIC ACID AND 6-I'IYDROXY-2 ,5 ,7,S-TETRAMETI-IY LCI'IROMAN- Z-CARBOXYLIC ACID BACKGROUND OF THEINVENTION The present invention pertains to antioxidant compositionswhich are useful in the preservation of edible fats and oils. It is wellknown that certain edible fats and oils such as, for example, lard,peanut oil, cottonseedoil, corn oil and the like are deficient innatural antioxidants. Due to this deficiency, such products are highlyvulnerable to deterioration in the presence of oxygen or air and willbecome rancid upon storage, thereby becoming discolored and developingunpleasant odors and flavors.

The present invention is predicated on the discovery that certaincombinations of ascorbic acid and rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid produce asynergistic antioxidant effect and are especially useful as theantioxidant component for compositions comprising in whole or partedible fats and oils.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directedto synergistic antioxidant compositions comprising mixtures of ascorbicacid and rac. 6-hydroxy-2,5,7,8-tetramethylchroman- 2-carboxylic acid.More particularly, the present invention is directed to compositionscomprising from about one part to about twenty parts by weight ascorbicacid for each part by weight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxy1ic acid. More preferred compositions inaccordance with the present invention comprise from about one part byweight to about ten parts by weight ascorbic acid for each part byweight of rac. 6-hydroxy2,5,7,8-tetramethylchroman-2- carboxylic acid.Especially preferred in accordance with the present invention arecompositions comprising two and one-half parts by weight ascorbic acidfor each part by weight rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

The synergistic antioxidant combination of the present invention isparticularly useful in the stabilization of edible fats and oils in thatthey are nontoxic, functional in fats and oils and free of undesirableorders, flavors and colors when incorporated in such substances in theamounts contemplated herein. Examples of edible fats and oils includelard, soy bean oil, cod-liver oil, corn oil, cottonseed oil, fish oil,safflower oil, rice oil, peanut oil, castor oil and the like. Theeffectiveness of the compositions of the invention in soy bean oil is ofcommercial significance since sales of soy bean oil constitutes about60% of the total sales of all edible fats and oils. The compositions ofthe invention are likewise effective in stabilizing against oxidationthose foods which contain a high percentage of oils or fats such as, forexample butter, margarine, cheese, mayonnaise, prepared salad dressings,potato chips, sausages and the like.

i To effectively inhibit oxidation in the above materials, mixtures ofascorbic acid and rac. 6-hydroxy-2,5,7,8-tetramethylchroman-Z-carboxylic acid in the percentages givenabove are added thereto in from about 0.01 percent by weight to about1.0 percent by weight, perferably from about 0.02 percent by weight toabout 0.2 percent by weight. These percent by weight ranges will varysomewhat according to the substance to be protected as is recognized inthe art.

The synergistic antioxidant compositions of the present invention areadmixed with the substance to be protected by methods commonlyrecognized in the art of food chemistry. The combination of the presentinvention has been found to be superior in effect to known antioxidantsand combinations of antioxidants used with the same materials asindicated above. The antiox idant combination of this invention isprepared by simple admixture of the active compounds. Rac. 6-hydroxy-2,5 ,7 ,8-tetramethylchroman-2-carboxylic acid can be preparedaccording to the following examples.

EXAMPLE 1 A solution of 2.4 g. (0.1 mol.) of rac. 6-acetoxy-2-hydroxy-2,5,7,8-tetramethylchroman in a total of 200 ml. ofdimethylsulfoxide was rapidly stirred as 32.5 g. (0.5 mol.) of granularKCN was added thereto by sifting so that a uniformly dispersedsuspension was obtained. The resulting suspension was cooled to 15centigrade as 47.0 ml of l2N aqueous H was added over 1.25 hrs. as theinternal temp. was maintained at 20 degrees centigrade. Tlc at thispoint showed a major, slowerrunning spot in addition to trace ofstarting material. The material was poured into diethylether and H 0.The ether soulutions were washed with water and brine, dried over NaSO,and stripped of solvent to yield rac.2-cyano-4-(5-acetoxy-2-hydroxy-3,4,6,- trimethylphenyl)-butan-2-ol as agum.

EXAMPLE 2 The cyanohydrin prepared in Example 1 was immediately taken upin 250 ml of methanol. This solution was cooled in an ice bath,saturated with anhydrous hydrochloric acid, stored for 18 hours at 2Cand stripped of solvent on a rotary evaporator (bath temp less than30C). The resulting gum was taken up in 250 ml of water, degassed,placed under nitrogen and heated for 2.0 hours at 40C to produce anaqueous suspension. The aqueous suspension was worked up and driedutilizing a solvent mixture of ethyl acetate and diethyl ether toproduce a mixture containing rac. 2-carbomethoxy-4- (2,5-hydroxy-3 ,5,6-trimethylphenyl )-butan-2-ol and rac.2-carbomethoxy-6-hydroxy-2,5,7,8-tetramethyl chroman. This mixture was atan solid. The tan solid was triturated with diethyl ether and thencrystallized from diethyl ether to given rac. 2-carbomethoxy-4-(2,5-hydroxy-3 ,5 ,6-trimethylphenyl -butan-2-ol as white prisms: pml35136.5C.

From the aqueous suspension prepared above, the ester rac.2-carbomethoxy-6-hydroxy-2,5,7,8-tetramethylchroman was isolated byfiltration of the aqueous suspension prior to working up.

EXAMPLE 3 The tan solid of Example 2 was suspended in ml. of 2N aqueousNaOH. The resulting solution was stirred under N for 24 hours, treatedwith 57 ml of 2N aqueous HCl followed by 10 m1 of saturated aqueousNaI-ICO solution to give a solution of pH 7.58.0. The solution wasextracted with diethyl ether, acidified with 2N aqueous HCl and againextracted with diethyl ether. These latter extracts were washed withbrine, dried (Na SO and stripped of solvent. The resulting 24.3 g of gumwhich partially crystallized was shown by tlc to be an approximatelyequimolar mixture of cyclized and uncyclized acids. Pure uncyclizedacid, rac. 2-carboxy- 4-(2,5-dihydroxy-3,4,6-trimethyl)-butan-2-ol wasisolated from this mixture by filtration of the aqueous suspensionobtained upon acidification, extraction with diethyl ether andcrystallization from diethyl ether, as a white solid which was verysusceptible to air oxidation: mp l77178C.

EXAMPLE 4 The crude mixture of acids in Example 3 and 0.57 g ofp-toluenesulfonic acid monohydrated in 300 ml of benzene was heated atreflux under N; with azeotropic removal of H for 1.25 hr. The cooledsolution was washed with a total of 300 ml of one-half saturated aqueousNaHCO and with brine. The aqueous solutions were treated with charcoal,acidified with 2N aqueous HCl and filtered to give rac. (i-hydroxy-2,5,7,8-tetramethylchroman 2-yl carboxylic acid as a light tan powder,mp. l89l90C.

EXAMPLE 5 Rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2- carboxylic acidalone and in combination with several other substances processingantioxidant activity was tested by means of the Swift Stability Test,commonly referred to as the Active Oxygen Method (AOM). This test, whichis described in Official and Tentative Methods. American Oil ChemistsSociety, Vol. 1, A.O.C.S. Champaign, Ill. 1964), consists in general ofbubbling air through a sample until rancidity develops. The AOM time inhours as expressed in the following table represents hours required toreach 70 P.V., i.e. 70 meg. peroxides at 98C. The data in Table Irepresents tests in soybean oil. For comparative purposes the value ofeach component is shown alone. All percents are percents by weight.

Table I Hours to reach 70 P.V.

The 190 hour value for the combination of 0.2 percent ascorbic acid and0.02 percent rac. 6-hydroxy- 2,5,7,8-tetramethylchroman-Z-carboxylicacid is considered exceptional.

In Table II, the activity of the combination of ascorbic acid and rac.6hydroxy-2,5.7.8-

tetramethylchroman-2-carboxylic acid was compared against a number ofantioxidant materials commonly utilized to stabilize edible fats andoils. Experiments were conducted with olive oil which contained mgpercent total tocopherol 16mg percent alpha and 4mg percent gamma) andstripped safflower oil. The latter was prepared on a rotary molecularstill at 270 under vacuum to remove tocopherols.

In Table III the synergistic antioxidant activity of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid in combination with ascorbicacid was clearly demonstrated by showing the activity combinations ofrac. 6-hydroxy-2.5,7,8-tetramethylchroman-2- carboxylic acid and othercommonly used antioxidants at their recognized effective levels. Thisexperiment was run in soybean oil at 98C.

Table III Additive Hours to reach RV.

None 5 0.02% Rac. 6-hydroxy-2.5.7,8- tetramethylchroman-2-carboxylicacid 27 0.02% Rac. 6-hydroxy-2.5.7.8- totramethylchroman-2-carboxylicacid 0.02% BHA 0.02% Rate. 6-hydroxy-2.5.7,8-tetramethylchroman-2-carboxylic acid 002% BHT 28 0.02% Rac.6-hydroxy-2,5.7.8 tetramethylchroman-2-carboxylic acid +0.02% AscorbylPalmitate 0.02% Rae. 6-hydroxy- .5.7,8- tetramethylchroman-2carboxylicacid +0.02% Propyl Gallate 0.02% Rac. 6-hydroxy-2,5,7,8-tetramethyclchroman2-carboxylic acid +0.02% TDPA 41 0.02% Rac.60hydroxy-2.5.7.8- tetramethylchroman-2-carboxylic acid +0.02% TBHQ 470.02% Rac. 6-hydroxy-2,5.7,8 tetramethylchroman-2-carboxylic acid +0.02%Ethylcnediaminetetra acetic acid 26 0.02% Rac. 6-hydroxy2.5 7,8tetramethylchroman-Z-carboxylic acid +02% Ascorbyl Palmitate 45 0.02%Rac. 6-hydroxy-2.5.7,8- tctramethylchroman-2-carboxylic acid +0.02%Ascorhyl Palmitate +0.02% TDPA 69 0.02% Rac. 6-hydroxy-2.5,7 8-tetramethylchroman-2carboxylic acid H),2% Ascorbic acid 200 In Table IV,the synergistic antioxidant activity of combinations of rac.6-hydroxy-2,5,7,8- tetramethylchroman-2-carboxylic acid and ascorbicchroman-2-caracid was again demonstrated in comparison with severalknown antioxidants utilizing as substrates a number of commonly usedoils.

Table IV Hours to reach 70 P.V. Cottonseed Peanut Lard Oil Oil AdditiveCorn Oil 90 l64 I50 boxylic acid +0.05% Ascorbic Acid 0.02% Rac.6-hydroxy-2.5.7.8- tetramethylchroman-Z-carboxlyic acid +0.01 AscorbicAcid 1 claim:

1. A process of preserving foodstuffs containing edible fats, edibleoils or both against oxidation which comprises adding thereto aneffective amount of an antioxidant composition consisting essentially ofrac. 6- hydroxy-2,5,7,8-tetramethylchroman-Z-carboxylic acid andascorbic acid.

2. The process of claim 1 wherein said antioxidant composition comprisesfrom about one part by weight to about twenty parts by weight ofascorbic acid per each part by weight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

3. The process of claim 1 wherein said antioxidant composition comprisesfrom about one part by weight to about ten parts by weight of ascorbicacid per each part by weight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

4. The process of claim 1 wherein the antioxidant compositions comprisesabout 2.5 parts by weight ascorbic acid per each part by weight of rac.-hydroxy- 2,5,7,S-tetramethylchroman-2-carboxylic acid.

5. A foodstuff containing one or more members of the group consisting ofedible fats and edible oils, normally subject to oxidativedeterioration, containing as an inhibitor for said deterioration aneffective amount of an antioxidant composition consisting essentially ofascorbic acid and rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

6. The foodstuff of claim 5 wherein said antioxidant compositioncomprises from about one part by weight to about twenty parts by weightof ascorbic acid of per each part by weight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

7. The foodstuff of claim 5 wherein said antioxidant compositioncomprises from about one part by weight to about ten parts by weight ofascorbic acid per each part by weight of rac. 6-hydroxy-2,5,78-tetramethylchroman-2-carboxylic acid.

8. The foodstuff of claim 5 wherein said antioxidant compositioncomprises about 2.5 parts by weight ascorbic acid per each part byweight 6-hydroxy-2,5,7,8- tetramethylchrornan-2-carboxylic acid.

1. A PROCESS OF PRESERVING FOODSTUFFS CONTAINING EDIBLE FATS, EDIBLEOILS OR BOTH AGAINST OXIDATION WHICH COMPRISES ADDING THERETO ANEFFECTIVE AMOUNT OF AN ANTIOXIDANT COMPOSITION CONSISTING ESSENTIALLY OFRAC. 6-HYDROXY-2,5,7,8-TETRAMETHYLCHROMAN-2-CARBOXYLIC ACID AND ASCORBICACID.
 2. The process of claim 1 wherein said antioxidant compositioncomprises from about one part by weight to about twenty parts by weightof ascorbic acid per each part by weight of rac.6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.
 3. The processof claim 1 wherein said antioxidant composition comprises from about onepart by weight to about ten parts by weight of ascorbic acid per eachpart by weight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylicacid.
 4. The process of claim 1 wherein the antioxidant compositionscomprises about 2.5 parts by weight ascorbic acid per each part byweight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.5. A foodstuff containing one or more members of the group consisting ofedible fats and edible oils, normally subject to oxidativedeterioration, containing as an inhibitor for said deterioration aneffective amount of an antioxidant composition consisting essentially ofascorbic acid and rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.
 6. The foodstuff of claim 5wherein said antioxidant composition comprises from about one part byweight to about twenty parts by weight of ascorbic acid of per each partby weight of rac. 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylicacid.
 7. The foodstuff of claim 5 wherein said antioxidant compositioncomprises from about one part by weight to about ten parts by weight ofascorbic acid per each part by weight of rac.6-hydroxy-2,5,78-tetramethylchroman-2-carboxylic acid.
 8. The foodstuffof claim 5 wherein said antioxidant composition comprises about 2.5parts by weight ascorbic acid per each part by weight6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.